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Topic: Blowing off too much yeast? (Read 2857 times)

I brewed up 2 Belgian dark strongs on Monday. One I could tell was going to need a blow off fairly quickly. The other went about 30 hours with no appreciable rise in kraeusen. I monitored it closely. It did not seem to be in danger. Sure enough in a matter of minutes while I was not watching it it blew its top! I cleaned the mess and put on a blow off then went to bed. This morning I found an even bigger mess with the blow off tube on the floor and tons of kraeusen, yeast... all over the fermenter and, fortunately, mostly contained in the water bath it was in.

Here is my concern. It seems to be no longer actively fermenting. I know activity is still going on but it is nowhere near as fierce as it was. There was a ton of yeast in the bottom of the water bath when I cleaned it out. Does the loss of this much yeast effect the fermentation and overall attenuation potential?

The reason I ask is something similar happened to me with a Belgian dark strong last year. I lost a lot of yeast through blow off and it ended up not attenuating enough. I suspected the yeast loss but just chalked it up to experience.

I am now making an emergency starter of some more yeast (wlp 530) to add back in and ramping the temp up a bit.

What temp did you pitch and ferment at? I don't think you need more yeast. Did you make a starter? It might be a combination of high fermentation temps and overpitching. There is no way all the yeast was blown out.

What temp did you pitch and ferment at? I don't think you need more yeast. Did you make a starter? It might be a combination of high fermentation temps and overpitching. There is no way all the yeast was blown out.

Give us some more info on recipe, etc.

Right, sorry. I posted about it elsewhere so I forgot to mention the details here.

It was two beers from one mash. I collected the wort in one kettle and then split it equally into two pots. Each had the same grist but had different flavors. The one that blew was a tangelo (zest) and chocolate flavored one. The chocolate seemed to be keeping the krauesen down as I have observed in past beers with this ingredient.

I made a starter, approx. 1500 ml though I already had a huge slug of yeast as I had done a starter previously but had to abort brewing. I would say I had about a cup and a half of slurry (350 ml) that I split between the two carboys. Again, WLP 530 yeast.

I pitched at 66°F for both and was monitoring it and slowly raising the temp. It is currently at 69/70°F and still letting it climb slowly.

O.G. on the mess (tangelo chocolate) was 1.078 the other was 1.070 (I will be adding additional fermentables to it in the form of pomegranate molasses when it slows down). The latter is still kicking rather hectically.

FWIW, I don't know if blowoff was really the cause of the low attenuation on your beers. I've had some massive blowoffs and I've never found a correlation between those and attenuation.

Yeah, it was only a guess. I know there can be many other variables. Just seeing a huge slurry of yeast in the blow off container (about a cup or more!) and then seeing very little activity afterward had me wondering...

I generally get the attenuation I expect but... I keep learning... I hope!

Yeah that wlp530 is one of my favorite Belgian strains, but man does it ferment VIOLENTLY!

+1

Did you check the gravity. It may be finished. Excessive blowoff doesn't necessarily indicate lacck of attenuation.

I am not assuming it is done yet. I am very patient with yeast and generally let them do their thing for 3 weeks (or more depending on the strain) before I even check the gravity. I am only talking about the previous similar situation. I KNOW there is still activity, it is just the precipitous drop in activity after losing so much yeast that had me concerned. I won't worry so much about it, mostly just curious if my hypothesis of blown off yeast equals problems with attenuation. The consensus seems to be the answer is no.

Well, I know it isn't done yet. It has been 2 weeks. Still tons of yeast in suspension but it is quite a bit higher than I would have hoped at this point. Actually the one that blew off a ton of yeast is a better off than the one that did not lose as much?!

The one I was concerned about is at about 1.018. The other is at 1.024! I know it will attenuate a bit farther given time but 7 and 13 points respectively? I don't think so. I seem to be suddenly having attenuation issues that I did not have before. My recent Scotch ale stalled out at 1.039 If I recall correctly.

As to mash temp it was 152F, and yes my thermometer was calibrated. I know it could have been lower for more fermentability. I was expecting drier due to the amount of simple sugars added to each. I grant though that some of the fermentables were guesses as to ferment-ability as I had no baseline. Biggest example being the pomagranate molasses added mid-ferment. Yes, that was the one that is at 1.024.

Well, time to prep for the next brews! I'll stop poking my nose in and let the wee beasties have some privacy to do their thing.